This disclosure generally relates to a reservoir for a hydraulic system. More particularly, this disclosure relates to control of fluid pressure to minimize a maximum pump inlet pressure.
A closed-loop hydraulic system includes a pump that drives fluid through the system. A reservoir is provided within the system to accommodate changes in the working fluid due to thermal expansion and contraction along with other variables. A bootstrap reservoir includes a piston movable between a high pressure chamber and a low pressure chamber to maintain a desired minimum pump inlet pressure. The minimum fluid pressure at an inlet to the pump is desired to provide efficient operation of the pump. A fluid pressure that is lower than desired can adversely affect pump operation and durability. Accordingly, a minimum pressure provided by the bootstrap reservoir is set well above the minimum desired inlet pressures. Because the low end of the pressure range is fixed by the bootstrap reservoir, the high end of the pressure range may be higher than desired. Higher pressures require that all system components be sufficiently robust to perform at the higher pressures. Accordingly, components in the fluid system are designed to withstand higher pressures that results in increased cost and weight.